Oviposition schedules, survivorship curves, and mortality factors within trees of two cerambycid beetles (Coleoptera: Cerambycidae), the Japanese pine sawyer, Monochamus alternatus hope, and sugi bark borer, Semanotus japonicus lacordaire

Abstract

SummaryOviposition schedules under laboratory conditions, survivorship curves, and mortality factors within trees of two cerambycid beetles, Japanese pine sawyer (JPS),Monochamus alternatusHope, and sugi bark borer (SBB),Semanotus japonicusLacordaire, were investigated. Average longevities of reared adults of JPS were 38.1 days for males and 42.3 days for females; those of SBB were 15.7 days for males and 23.8 days for females. It was confirmed that the JPS must feed on the pine branches for full maturation after emergence, but SBB need not; they are able to lay eggs soon after emergence. The average fecundities of JPS and SBB were 32.9 and 90.5, respectively. Thus, the JPS lay fewer eggs for a long time with continuous maturation feeding, whereas the SBB lay more eggs for short time without maturation feeding. Average survivorship curves of JPS within dead pine trees in 8 pine forests were theDeevey's B type, showing a constant mortality through the pre‐imaginal stages in the trees. On the other hand those of SBB in 4 cedar stands approached theDeevey's type, suggesting that the high mortality occurred at an early stage in the trees. Average mortalities of JPS between the appearance of oviposition scars and adult emergence in 8 forests ranged from 62.3% to 95.2%. Intraspecific ompetition of JPS resulting from overcrowding in dead pine trees appeared to be main mortality factor. For SBB, as most larvae were killed by resin flow in living trees, this appeared to be the main mortality factor for this species.